CVE-2026-50501 in Windows
Summary
by MITRE • 07/14/2026
Stack-based buffer overflow in Windows Resilient File System (ReFS) allows an unauthorized attacker to execute code locally.
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Analysis
by VulDB Data Team • 07/14/2026
A stack-based buffer overflow vulnerability exists within the Windows Resilient File System implementation that enables local privilege escalation through arbitrary code execution. This flaw occurs when the ReFS file system processes certain malformed input data structures, leading to memory corruption in kernel-mode components. The vulnerability stems from insufficient bounds checking during buffer operations within the file system's kernel drivers, creating an exploitable condition where attacker-controlled data can overwrite adjacent stack memory locations.
The technical implementation of this vulnerability involves improper validation of input parameters when processing ReFS metadata structures, particularly during file allocation and directory traversal operations. When malicious data is passed to ReFS functions, the stack buffer receives more data than its allocated capacity, causing adjacent memory to be overwritten with attacker-controlled values. This overflow can be leveraged to manipulate execution flow by overwriting return addresses or function pointers stored on the stack, ultimately allowing code execution with kernel privileges.
The operational impact of this vulnerability is significant as it provides local attackers with a path to escalate privileges from standard user level to system level access. Attackers can exploit this condition without requiring network connectivity, making it particularly dangerous in environments where local access is possible. The vulnerability affects Windows operating systems that implement ReFS functionality, including various server and desktop editions supporting this file system. Successful exploitation results in complete system compromise, enabling attackers to install malware, modify system files, or establish persistent backdoors.
Mitigation strategies should focus on immediate patch deployment from Microsoft security advisories, as well as implementing additional protective measures such as kernel address space layout randomization and data execution prevention. System administrators should also consider disabling ReFS functionality if not required for specific operations, though this may impact storage performance and reliability features. Network segmentation and privilege separation practices can help limit the potential impact of successful exploitation attempts. This vulnerability aligns with CWE-121 stack-based buffer overflow classifications and represents a technique that could be categorized under ATT&CK tactic TA0004 Privilege Escalation through kernel-mode exploitation methods. Organizations should prioritize patch management processes and maintain current threat intelligence to address similar vulnerabilities in file system implementations.